Numerical modelling of volume changes at early ages-Potential, pitfalls and challenges

Abstract

For quantification of early deformations of hardening cement-based systems a number of conceptual and numerical models have been proposed. In this contribution some aspects of these models with be discussed and evaluated with respect to the mechanisms that are considered to be responsible for volume and length changes at early ages. Emphasis will be on systems hydrating under sealed conditions. The fact that volume changes at early ages, and more in particular autogenous shrinkage, should be considered as the response of a continuously changing system is discussed. These changes concern at least the pore system and the state of moisture in the pore system. Numerical models should, therefore, be able to simulate the evolution of the pore system with progress of the hydration process explicitly. Parallel with the modelling of the evolution of the pore system, c.q. the microstructure, the state of stress and associated deformations should be considered. The potential of numerical simulation models to deal with this coupled problem is discussed. Pitfalls encountered when developing and validating numerical simulation models will be addressed and discussed. The potential of numerical models is illustrated with examples.